Airplane heater



Aug. 28, 1945. V O H 2,383,650

AIRPLANE HEATER Filed March 30, 1943 2 Sheets-Sheet 1 Aug. 28, 1945. F. o. HESS 2,383,650

AIRPLANE HEATER Filed March 50, 1943 2 Sheets-Sheet 2 INVENTOR file-00m 0 #555 I 4 ATTORNEY PatentesiAug- 1945' UNITED STATES PATENT yOFFlCE j ,z mi xmbiao tititffiiifiih'itt'uzrepmiifi acorpora tionof lennsylvani a Application March 30,1943, serial No. 481,017 reclaims. (c1. ear-33) i The general object of the present invention is to provide an improve heater fox-use in airplanes, and is especially useful for heating cabin spaces oi transport airplanes, war plane space provided for pilots, observers and gunners, and/or ammunition and in defrosting operations. More particularly, the present invention has-for its ma- Jor object to provide improvements in an airplane heater of a general type like that illustrated in Heas and Townsend Patent No. 2,314,089 granted March 10, 1948.

An airplane heater of the above mentioned type is a eompact light'weight structure comprising a combustion chamber into which a. combustible mixture of combustion air and atomize'd gasolene is passed and from which products of combustion are withdrawn in such manner as'tomaintain a pressure in the combustion chamber which is approximately equal to, butpreferably is slightly less than the pressure of the atmosphere in the space in which the heater is located. Fan means for maintaining a suitable volumeof fiow'of combustible mixture through the combustion chamber of the heater and for moving air through the air-heating space of the'heater contribute to a relatively great heating capacity of the heater per unit of bulk and weight.

Specific objects of'the present invention are to efi'ect a further increase in the heating capacity of an airplane heater of given size and weight, to simplify the regulation and control of the heater, and to provide the heater with improved To permit eilective heater operation when the airplane is grounded or the fan-driving motor is otherwise inoperative or ineffective, I may provide an auxlliaryelectric motor which can be appreciably smaller and lighter than it would need to v be if it were the only fan driving motor for the heater.

In the ordinary practical use of sucha heater the continuous maintenance of desirable operating conditions presents serious control problems as a result of the wide and rapidly occurring changes in pressure and temperature of the atmosphere enveloping the airplane in which the heater is used. At sea level the normal atmospheric air pressure is approximately; 15 pounds' 'and at 40,000 ft. above sea level, it is less than 3 pounds per square inch. when the atmospheric temperature at a sea level point on the earths surface may be 100 F., for example, the'temperature at a point 40,000 ft. above the first mentioned point will normally be of the order of 40 to 60 degrees F. below zero, but at times it may be as much as 140 F. below zero. I A decrease in air temperature from plus 40 F. to 40 F. below zero, means an air density decrease of about 25%.

' Furthermore, variation in the speed of the airplane relative to the air in which it is moving fan driving means. A still more specific object of thepresent invention, which contributes to the attainment of the previously mentioned objects. is to provide a heater of the above mentioned type with a fan driving air motor actuated by air fiow along apath of fiow extending from a scoop or may tend to create a substantial change in the pressure in the combustion space of. the airplane heater. Thus, for example, it has been found in the use of a heater of the general type mentioned, that a sharp airplane turn "may make a momentary change, equal to a nine inch head of water, in the pressure in the outlet opening at the skin of the airplane through which products of combustion are discharged from the airplane 5 heater.

ram inlet opening in the skin or shell of the airplane, and an outlet opening in the said skin or shelhwith said inlet and outlet so relatively disposed that the air pressure in said inlet substantially exceeds that in said outlet in the normal operation of the airplane.

The air motor employed in the heater may take various forms. -For'example, it may be of a known type comprising a peripheral wheel with buckets 0r vanes against which the motor driving air is discharged'in the form of a tangential jet. In thedesirable form of the invention illustrated in the accompanying drawings, however, the air motor comprises a wheel formed with" curved channels which extend outwardly from a central air-receiving portion of the wheel and discharge the air received at the periphery of the 'wheel.

a claims annexed hereto and forming a part of this specification. For a better understanding of the invention however, its advantages andspecific obiects obtained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated a preferred embodiment of the invention;

- Fig. 1 is a sectional elevation;

Fig. 2 is an inverted plan view;

Fig. 3 is a section on the line 3-3 of Fig. 1;

Fig. 4 isasection on the linel-l ofFlg. 1: and

Fig. 5 is a view taken similarly to Fig. 4 and illustratingamodification.

The embodiment of myinvention illustrated somewhat diagrammatically in Figs. 1-4, mm!

metal and enclosing a ran chamber B and having I I a central inlet opening C in one side wall or said chamber for the infiow of air to be heatedfrom the airplane cabin 'or other space in which the heater is located. The casing A supports suitable bearings D for a main heater shait E coaxial with inlet C and extending through chamber B. The

. 2,888,050 r r prises a heater shell 01'- casing A formed or thin K of a eentriiud as K. latter coaxi v ai pelle'r element K. The latter includes a'hub portion K secured to the shaft Eand a radial plate like body extending away from the h'ubto the inner edge of the chamber K and provided at its side remote from the chamber B with radially ex-v shait E supports an air circulatim; fan wheel 1'' rotating in the chamber B and shown as comprising adisc at the side oi the chamber B remote from the inlet and peripheral blades or vanes I" each connected at one end ,to said disc and extending across the chamber B. The fan wheel 1'' shown is of a well known type adapted to draw air into chamber B through its inlet C and to discharge the air into an annular air heating space B surrounding the tan wheel I". g

In the construction shown the air discharged at its periphery by the fan wheel F, moves outward from the latter into anannular outlet chamber or space G which communicates with the chamber B through the spaces between air heating tubes or elements H parallel to and suitably spaced about the heater axis. Preferably and as shown. each tube H is formed 01' thin metal and is provided with external thin, circumierentially extending metal fins H each extending radially away from the outer surface of each vtube H for a suitable distance. That distance may be approximately equal to the tube diameter and in such case adjacent tubes K may have their adiacent sides displaced by a distance approximately equal to twice the tube diameter, as shown in Fig. 2. However, the particular spacing of the tubes H, and the form and dimensions of the fins H are not essential characteristics of the heater. The heater'is provided with one or more outlets G from the space G through which the heated air ispassed to the space or spaces to be heated.

The tubes H receive hot gases irom the combustion chamber I of an annular burner and discharge into an annular collecting chamber H having a tubular outlet pipe H. The burner comprises an inlet chamber I separated from the combustion chamber I by an annular orifice wall 1 a through which a combustible mixture of air and,

atomized gasolene passes from the inlet chamber 1 into-the combustion chamber I, entering the latter in the form of a multiplicity oi fine jets. Advantageously, the orifice wall is like that of the burner shown in said Patent No. 2,314,089111 that it is formed of ceramic plates having grooves at their sides which form the orifices P oi said wall. The orifice wall shown in Fig. l diilers in form from the burner orifice wall of said prior ber adjacent to the orifice wall is formed 01' reiractory material I. The remaining portion oi the inner wall of the combustion chamber is formed of metal and is provided with heat dissipating ribs or fins I which extend into the outer portion oi. the fan chamber B.

' The burner inlet chamber 1' receives the combustible mixture through a plurality of tubular tending blades or vanes K. The fan casing of fan K is formed with a central air inlet K at its sideremote from the chamber B through which combustion air enters the impeller chamber in which the blades K'move. A gasolene supply nozzle L discharges ajct oi gasolene against the inner portion of the impeller or 'wheel of fan K, which mechanically atomizes the gasolene jetted against it and mixes it with the combustion air which it tube L of elastic material extending circularly about the pump axis and having one end connected to a gasoiene supply pipe L and havins' its other end connected to 'the discharge nozzle L. In each rotation the eccentric l1. moves a slug oi gasolene through the tube 1. and into the discharge nozzle L. as a result of the action oi the high point of the eccentric IF in compressing and thereby closing the passage through the adjacent portion of the tube. As shown. he tube L is directly engaged at its inner side by a floatin thrust ring L which surrounds the eccentric L, and a series of ball or roller elements L are interposed between the eccentric and ring. The

ring L and balls L reduce the frictional force tendencyot the eccentric I? to give lon itudinal {movement to the tube 1?. The tube L- may be :lo'rmed oi neoprene or other elastic material subjected.

As best shown in Figs. 1 and 4. the cylindrical casing oi the gasolene pump L is mechanically connected tothe adjacent side of the casing of the fan K through a cylindrical casing part LK. .lhe latter is cut away to provide an air inlet LK through which air passes to the fan casing inlet K from the space in which the heater is located. The efiective area of the inlet ports LK' maybe regulated by the annular adjustment of a slotted cylindrical damper M, surrounding the casing.

parts LR, and provided with an arm K through which the damper M may be annularly adjusted about the heater axis to variably throttle the supply of combustion air to the heater. In some cases the damper It may be adjusted manually. but ordinarily it is advantageous to adjust it automatically in response to variations in the pressure oi the atmosphere or in automatic response both to variationsin atmospheric pressure and in temperature variations. As shown in Figs. 1 and 4, the damper M is automatically adjusted to increase the volume of air fiow-throughthe port LK' as the pressure of the-atmosphere enveloping the heater diminishes, by a bellows element M which expands and contracts longitudinally as the surrounding atmospheric pressure decreases-and in and its other end conduits K extending from the annular chamber armM.

creases. The bellows M has one stationary end movable and connected to the with the'shatt: Ill and comprises] awheel or.im-

wheel of an air motor which rotates the fan wheels F and K and the gasolene pump mem.-'

ber L. As shown, the air motor impeller wheel comprises a thin metal body 0'. having a conical central portion and a radial outer portion and blades or vanes 0 carried by said body 0' at its front or outer side which extend from the central portion of the wheel to its periphery. The outer end of the vanes 0 similarly diverge from the radial planes respectively n contact with the inner. ends of the vanes, 'so that air moving outward through the passages between adjacent vanes subject the wheel 0 to a rotative torque.

A thin metal casing structure P, co rates with the impeller body 0' to form a wheel chamber through which the vanes O? sweep when the impeller is in rotation. The casing structure P the motors may be appreciably smaller, less powerful and less expensive than it would need.

to be ifit were to be used as the soledriving means for the shaft E.

structed in accordance with the present invention may vary widely as conditions make desirable.

By way of example and illustration, it is noted that for certain military, present day uses, a heater of the general form and relative proportions shown in Figs. 1 and 2, may have the dianieter of the outer wall of the chamber G about proximately 50,000 B. t. u.s per hour in its combustion chamber.

is shaped to provide a discharge chamber P surrounding the path of movement of the vanes 0' and an inlet passage P discharging an axial stream of air against the central portion of theair motor impeller. The air moving through the passage P is received from a scoop or ram inlet P external to the skin or shell Q of the airplane, and facing in the direction of airplane movement, so that the resistance of the air to the airplane movementincreases the air pressure in the inlet P The air motor casing is also shaped to provide a discharge passage P receiving air from the delivery chamber 1? and extending through the airplane shell Q and terminating externally of the latter in an open discharge end P, facing in a direction opposite to that in which the airplane is moving. The movement of the airplane relative to the enveloping atmosphere thus lowers the air pressure in the outlet P and increases the air pressure in the inlet P The pipe H discharging products of combustion passing through the tubes H and chamber H has its discharge end H extending into the portion of the passage P external to the air plane shell Q, and so disposed that the air flow through the passage P will produce an aspirating effect on the gases moving through pipe HE. A butterfly damper R. in the passage P forms a means for regulating the volume of flow through the air motor 0 and thereby regulating the speed of rotation and available torque of the heater driving'shaft E. The damper R may be subject to manual control; though in some cases it may be well to adjust the damper automatically so as to vary the speed of the shaft E in accordance with the variations in temperature which determine the desired heat output of the heater.

To permit the operation of the heater when the airplane is grounded orthe heater air motor 0- to connect the shafts S and EA when the airmotor is ,out of operation and be automatically operated to disconnect those shafts when the air motor 0 comes into operation and increases the speed of the shaft E. For its intended use,

' To rotate the fan -wheels F and K and the which may be of the order of 4,000 revolutions per minute, about one-quarter horsepower must be supplied by the air motor 0, inlow altitude operation. With the airplane moving at a speed of 300 miles .per hour in an atmosphere having a pressure which is of the order of 14 ounds per square inch, the pressure in the ram inlet P may exceed the pressure of the atmosphere by an amount. corresponding to a water head of about twenty-two inches and the pressure in the outlet-P may be less than the atmospheric pressure by an amount corresponding to a water head of the order of twenty-two inches. Under such conditions a suitably designed air motor 0 of the proportions and dimensions suggested should be capable of developing about two horse power. That is ample for practical purposes, in which allowance must be made for unusually heavy frictional loads at times, and for the energy required for the delivery of an adequate amount of properly heated air under adverse conditions.

The power developed by the air motor will diminishes the airplane altitude increases, and there is a generallysimilar,reduction in the energy required to move the air heated through the heater. In general, however, the frictional load will remain constant. However,.the increasing relative importance of the frictional load as the altitude increase may be compensated for more or less, by reducing the throttling effect of the damper 13., which normally will be adjusted into its maximum throttling position or low. altitude operation. As will be understood, all of-the dimensions and operational data mentioned above have been given by way of illustration-and ex- 7 ample, and not by way of limitation.

In-general, as the airplane altitude increases, the damper M should be adjusted to diminish its throttling efiect. Such adjustment will be automatically effected by the expansion of the bellows member M of Figs. 1 and 4. When the in the rate of gasolene supply, may be advantageous, as the resultant "increase in the fuel richness of the combustible. air and gas mixture delivered to the combustion chambenfacilitates ignition.- Such an adjustment in response to temperature may be automatically effected by means of the character illustrated diagrammatically in Fig. 5, in which a bimetallic, thermostatic element U is employed to give opening and closing adjustment to the damper M as the tem- The form and dimensions 'of a heater [conperature of,the element U increases and decreases.

Aswill be apparent, ordinarily the amount of I with the pressure of the atmosphere envelopingthe airplane. When the heater is located in a supercharged cabin however, it may sometime be advantageous to automatically adjust both of the dampers M and R in some cases by means responsive to the cabin temperature and operating in the general manner in which the above mentioned thermostat U operates.

, The motor S may be dispensed with in some cases, but is advantageously employed in many cases for reasons already made apparent. When included in the heater it may well be provided in some cases with a coil and current delivery means 'I for supplying energizing current to a spark igniter (not shown) for initiating combustion in the combustion chamber of the heater. After ignition is well established, the refractory material burner parts attain temperatures ample to maintain ignition.

aseacao fan means to provide a combustible mixture of air and fuel in said chamber and for discharging products of combustion from said radiator to the exterior of the airplane, fan means for moving through said space air to be heated, a translating device for operating both of said fan means, and conduit means through which air may pass from the exterior of the airplane to mounted on the floor or ceiling or alongside a side wall of an airplane cabin space, the heater may well be flattened or pancaked," by reducing its dimensions in the direction of the length of the .shaft E relative to its dimensions transverse to said shaft. Thus when the diameter of the inlet 0 is increasedrelative to the diameter of the fan K, the latter may approach the position in which it is in the same general plane.

' as the burner of the heater without objectionably impeding the movement of airinto the fan chamber B. As will be apparent, the motor S need not have its shaft in alignment with the shaft E but may be belt connected to the latter and in such case may occupy any convenient position relative to the heater body.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now' known to me, it will be apparent to thoseslnlledin the art that changes maybe made in the form of the apparatus disclosed withoutv departing from the spirit of my invention, as set forth in the appended claims, and that in some cases certain features of my invention may be .used to advantage without a corresponding use of other features.

' Having now described claim as new and desire to secure by Letters Patent, is:

1. The combination with an airplane, of a heater within said airplane and comprising my, invention, what I structure providing a combustion chamber and 15 the space for transferring heat'from a heating said device and from which air may be discharged to the exterior of the airplane, said device and conduit means being so constructed and arranged that flow of air therethrough, developed during flight of the airplane, will actuate said device to operate both of said fan means.

3. The combination with an airplane, of a heater therein including structure providing an air heating space and a heating radiator including a combustion chamber, said radiator being in heat exchange relation with said space for trans- 1 conduit means through which air may pass from the exterior of the airplane to said device and from which air may be discharged to the exterior of the airplane, said device and conduit means being so constructed and arranged that flow of air therethrough, developed during flight of the airplane, will actuate said device to operate said pump and both of said fans.

4. The combination set forth in claim 2, in

which said radiator and air heating space are disposed about and envelop said translating device.

5. The combination set forth in claim 2, including an electric motor, and means for connecting and disconnecting said motor to and from said fan means.

6. The combination set forth in claim 3, including an electric motor, and means for connecting and disconnecting said motor to and from said fans and said pump. p

7. The combination set forth in claim 2, including passage means through which products of combustion are discharged from said radiator, and in which said passage. means is associated with said conduit means through which air is discharged from said translating device to the exterior of the airplane, so that air flowing through said conduit means from said translating device produces a suction effect in said passagemeans tending to reduce the pressure in saidradiator.

8. The combination with an airplane, of a heater therein including structure providing a heating radiator and an air heating space, the radiator being in, heat exchange relation with medium in the radiator to air in the space, means to supply the heating medium for the radiator, fan means for moving air to be heated through the space, a translating device for operating the fan means, and conduit means through which air may pass from the exterior of the airplane to the device and from which air may be discharged to the exterior of the airplane, the device and conduit means being so constructed and arranged that flow of air therethrough, developed during flight of the airplane, will actuate the device to operate the fan means.

9. The combination set forth in claim 8inc1uding an electric motor associated with the fan means and operable to drive the latter when the airplane is grounded.

10. The combination set forth in claim 8, in which the heating radiator and air heating space are disposed about and envelop the translating device.

11. The combination with an airplane, or a heater therein including structure providing a heating radiator and an air heating space, the radiator being in heat exchange relation with the space for transferring heat from heated products of combustion in the radiator to air in the space, means to supp heated products of combustion for the radiator, piping through which the products of combustion may pass from the radiator to the exterior of the airplane, fan means for moving air to be heated through the space, a translating device for operating the fan means, and conduit means through which air may pass from the exterior of the airplane to the device and from which air may be discharged to the exterior of the airplane, the device and conduit means being so constructed and arranged that flow of air therethrough, developed during flight of the airplane, will actuate the device to operate the fan means, and the discharge end of the piping terminating within the conduit means so that air discharged from the device to the exterior of the airplane may be utilized to aspirate products of combustion through the piping from the radiator.

12. The combination set forth in claim 11 including means to adjust the rate at which air flows through the conduit means and hence the aspirating efiect produced for exhausting products of combustion through the piping from the 25 radiator.

FREDERIC O. HESS. 

